鉴定 ErbB/MAPK 信号级联反应作为犬膀胱癌的治疗靶点。
Identifying the ErbB/MAPK Signaling Cascade as a Therapeutic Target in Canine Bladder Cancer.
机构信息
Flint Animal Cancer Center, Department of Clinical Sciences (K.E.C., B.G.H., D.L.G., D.L.D.), and Cell and Molecular Biology Graduate Program (K.E.C., D.L.G., D.L.D.), Colorado State University, Fort Collins, Colorado; and University of Colorado Cancer Center, Aurora, Colorado (D.L.G., D.L.D.).
Flint Animal Cancer Center, Department of Clinical Sciences (K.E.C., B.G.H., D.L.G., D.L.D.), and Cell and Molecular Biology Graduate Program (K.E.C., D.L.G., D.L.D.), Colorado State University, Fort Collins, Colorado; and University of Colorado Cancer Center, Aurora, Colorado (D.L.G., D.L.D.)
出版信息
Mol Pharmacol. 2019 Jul;96(1):36-46. doi: 10.1124/mol.119.115808. Epub 2019 May 2.
Transitional cell carcinoma (TCC) of the bladder comprises 2% of diagnosed canine cancers. TCC tumors are generally inoperable and unresponsive to traditional chemotherapy, indicating a need for more effective therapies. BRAF, a kinase in the mitogen-activated protein kinase (MAPK) pathway, is mutated in 70% of canine TCCs. In this study, we use BRAF mutant and wild-type TCC cell lines to characterize the role of BRAF mutations in TCC pathogenesis and assess the efficacy of inhibition of the MAPK pathway alone and in combination with other gene targets as a treatment for canine TCC. Analysis of MAPK target gene expression and assessment of extracellular signal-regulated kinase (ERK) 1/2 phosphorylation following serum starvation indicated constitutive MAPK activity in all TCC cell lines. BRAF mutant TCC cell lines were insensitive to the BRAF inhibitor vemurafenib, with IC values greater than 5 M, but exhibited greater sensitivity to a paradox-breaking BRAF inhibitor (IC: 0.2-1 M). All TCC cell lines had IC values less than 7 nM to the mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor trametinib independent of their BRAF mutation status. ERK1/2 phosphorylation decreased after 6-hour treatments with MAPK inhibitors, but rebounded by 24 hours, suggesting the presence of resistance mechanisms. Microarray analysis identified elevated expression of the ErbB family of receptors and ligands in TCC cell lines. The pan-ErbB inhibitor sapitinib synergized with BRAF inhibition in BRAF mutant Bliley TCC cells and synergized with MEK1/2 inhibition in Bliley and BRAF wild-type Kinsey cells. These findings suggest the potential for combined MAPK and ErbB receptor inhibition as a therapy for canine TCC. SIGNIFICANCE STATEMENT: The results of this study (1) identify a novel combination strategy for canine bladder cancer treatment: targeting the ErbB/MAPK signaling cascade and (2) establish the utility of canine bladder cancer as a naturally-occurring model for human MAPK-driven cancers.
膀胱移行细胞癌（TCC）占犬类癌症诊断的 2%。TCC 肿瘤通常无法手术，对传统化疗无反应，表明需要更有效的治疗方法。BRAF 是丝裂原活化蛋白激酶（MAPK）途径中的一种激酶，在 70%的犬 TCC 中发生突变。在这项研究中，我们使用 BRAF 突变和野生型 TCC 细胞系来描述 BRAF 突变在 TCC 发病机制中的作用，并评估单独抑制 MAPK 途径以及与其他基因靶点联合作为治疗犬 TCC 的疗效。MAPK 靶基因表达的分析和血清饥饿后细胞外信号调节激酶（ERK）1/2 磷酸化的评估表明，所有 TCC 细胞系均存在组成性 MAPK 活性。BRAF 突变 TCC 细胞系对 BRAF 抑制剂 vemurafenib 不敏感，IC 值大于 5μM，但对突破性 BRAF 抑制剂（IC：0.2-1μM）表现出更高的敏感性。所有 TCC 细胞系对丝裂原活化蛋白激酶激酶（MEK）1/2 抑制剂 trametinib 的 IC 值均小于 7 nM，与 BRAF 突变状态无关。MAPK 抑制剂处理 6 小时后 ERK1/2 磷酸化减少，但 24 小时后反弹，表明存在耐药机制。微阵列分析鉴定出 TCC 细胞系中 ErbB 家族受体和配体的表达升高。在 BRAF 突变的 Bliley TCC 细胞中，泛 ErbB 抑制剂 sapitinib 与 BRAF 抑制协同作用，在 Bliley 和 BRAF 野生型 Kinsey 细胞中与 MEK1/2 抑制协同作用。这些发现表明，联合 MAPK 和 ErbB 受体抑制可能成为犬 TCC 的一种治疗方法。意义：这项研究的结果（1）确定了犬膀胱癌治疗的一种新的联合策略：靶向 ErbB/MAPK 信号级联，（2）确立了犬膀胱癌作为人类 MAPK 驱动的癌症的自然发生模型的效用。
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